n = gets.to_i
sn = n * (n - 1) / 2
t = Math.sqrt(n).to_i
res = 0
t.times do |x|
    x += 1
    if n % x != 0 then
        next
    end
    if sn % x == 0 then
        res += x
    end
    ax = n / x
    if ax != x && sn % ax == 0 then
        res += ax
    end
end
puts res